New Observatory Set to Scan Solar System’s Edge

A new space observatory that aims to investigate the edge of the solar system is poised to launch Sunday.

NASA's $169 million Interstellar Boundary Explorer (IBEX) spacecraft is designed to measure particles bouncing back from the nether regions of the solar system, where the hot wind from the sun slams against the cold wall of interstellar space. The coffee table-sized observatory is set to launch Oct. 19 at 1:48 p.m. EDT (1748 GMT) aboard a Pegasus XL rocket from the Kwajalein Atoll, a part of the Marshall Islands in the Pacific Ocean.

"IBEX is really a mission of discovery," said Nathan Schwadron, IBEX co-investigator and chief of the spacecraft?s science operations center lead at Boston University, in a Friday teleconference. "We really have never seen the structures that surround and protect our entire solar system. We know very little about what we're going to see."

The sun unleashes a protective bubble of charged particles around the solar system called the heliosphere, which shields the planets from deadly cosmic rays. Over the past 15 years, the pressure from this solar wind has been diminishing, and is now at the lowest level measured since the beginning of the space age, said Dave McComas, IBEX principal investigator at the Southwest Research Institute in San Antonio, Tex.

"We don?t know whether we're on the verge of a larger reduction or whether we're near the bottom," McComas said. "What's most likely is that there are natural variations in this solar wind pressure and that over time it will either stabilize or start going back up, but nobody really knows. So it's an interesting time to live in."

The scientists hope the new spacecraft will shed new light on this decline, as well as how changes in the heliosphere may affect Earth.

To study the dynamic interactions taking place between the heliosphere and the rest of the galaxy, IBEX is outfitted with two bucket-sized sensors that will capture neutral hydrogen atoms travelling back toward Earth from the edges of the solar system.

Luckily, to study the distant edge of the solar system, IBEX doesn't have to travel nearly that far. The spacecraft will rocket to an orbit 200,000 miles (322,000 km) above the Earth, high enough to escape contamination from our planet's magnetic field. The moon, for comparison, orbits about 240,000 miles (385,000 km) from Earth.

"Every six months we will make global sky maps of where these atoms come from and how fast they are traveling," said Herb Funsten of Los Alamos National Lab, which built IBEX's High Energy Neutral Atom Imager. "From this information, we will be able to discover what the edge of our bubble looks like and learn about the properties of the interstellar cloud that lies beyond the bubble."

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